I have my audio in m4a format, i want to convert mp3 format i tried in google, some online link for converting.. its working but audio quality is very poor, i changed high quality option too.. but quality not good, friends if u have any link or source discuss with me too..[/font][/size]

if the original file is already too optimized, no software would be able to "convert" it to file with "better" quality...conversion from one compressed file to another will only make the sound quality lower.